At present, flat-panel televisions such as liquid crystal televisions and plasma televisions have generally been spread. Corresponding to such a tendency, characteristics such as high-definition display, power saving, and long-period reliability are required for the flat-panel televisions. Therefore, for component members used in the flat-panel televisions, various characteristics such as transparency, birefringence index, and heat resistance have been required. Particularly, for a planarizing film, a phase difference film, and the like used in a liquid crystal display, transparency, heat resistance, and handling properties are required.
A hyperbranched polymer has characteristics such as an excellent solubility, and a solution viscosity and a melt viscosity both extremely small. Therefore, the hyperbranched polymer is excellent in handling properties, and a development thereof into a functional material is expected. As one example of the hyperbranched polymer, a triaroylbenzene-skeleton polymer is reported (see Patent Document 1 and Non-patent Document 1). The polymer has such advantages as not only excellent solubility, but also high heat resistance and capability of being simply synthesized. However, the polymer has the problem that a film of the polymer has low transparency for use in an optical film for a liquid crystal display or the like.